Added dependency on facebook/xhprof which already contains required autoloaded files. Added config value to customize Response header name or disable it. Response header is now added also  in prod mode
Possible fix for facebook/xhprof dependency version
Added request query argument configuration
Updated docs
Response header: Changed from complete URL to xhprof Run ID due oto security reasons
Merge pull request #40 from maxromanovsky/multiple-fixes

Multiple fixes (added dependency on facebook/xhprof, added ability to send custom header in response & enable xhprof for requests with particular query argument)